Control device for auxiliary circuit breaker switches

ABSTRACT

Control for auxiliary switches on circuit breakers wherein the control is placed so that it will be dependent on the detection of an appreciable current in a conductor of the circuit of an auxiliary switch of the circuit breaker.

United States Patent 1 Thuries et al.

CONTROL DEVICE FOR AUXILIARY CIRCUIT BREAKER SWITCHES Inventors: Edmond Thurles, 69-Pusignan;

Francois Joly, 69-Lyon 6e, both of France Assignee: Delle-Alstholn, Villeurbanne, France Filed: Jan. 10, 1972 Appl. No.: 216,475

Foreign Application Priority Data 200/144 AP, 176, 148 R, 148 A, 148 B; 335/16,l47,18,19

[ 1 June 5, 1973 [56] References Cited UNITED STATES PATENTS 2,892,913 6/1959 Thommen...- 2,023,070 12/1935 Goldsborough 3,491,315 l/l970 Kesselring ..335/l9 FOREIGN PATENTS OR APPLICATIONS l/l935 Great Britain ..200/ 148 J Primary ExaminerJ. D. Miller Assistant Examiner-Harvey Fendelman Attorney- Richard C. Sughrue, Gideon Franklin Rothwell,John H. Mion et a].

[5 7] ABSTRACT Control for auxiliary switches on circuit breakers wherein the control is placed so that it will be dependent on the detection of an appreciable'current in a conductor of the circuit of an auxiliary switch of the circuit breaker.

.8 Claims, 8 Drawing Figures mm Jun e 5.101s 3,737,819

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, l CONTROL DEVICE FOR AUXILIARY CIRCUIT BREAKER swrrcnas BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates to the control of auxiliary switches associated with high-voltage circuit breakers, such as the switches provided to connect or disconnect auxiliary resistances mounted parallel with principal cutoff chambers and, more precisely, the control of the opening of these auxiliaryswitches.

2. DESCRIPTION OF THE PRIOR ART When one opens the switch, it is in effectin portant to reduce the duration ofcurrent passage in the auxiliary resistances so as to limit the thermal stresses of the latter, especially in the case of a cutoff in opposite phase. The circuit of the auxiliary resistances can be opened only after the cutoff of the principal current but, when the latter is interrupted, the circuit of the resistances must be opened rapidly in order to limit the energy developed in the resistances.

One can predetermine the instant at which the cornmangi for the opening of an auxiliary switch will be triggered after the process of opening the circuit breaker has started up, but one must keep in mind here the possible variations of the principal cutoff process and to fix this instant relatively late, which leads to the exaggers ated dimensions of the auxiliary resistances.

It has already been proposed to control, at'a much more precise instant, the opening of an auxiliary circuit breaker switch by placing the control so that it will be dependent on the detection of an appreciable current in the circuit of this auxiliary switch and, for this purpose, a control coil has been placed in series in this circuit.

But, since rapid current variations develop in the auxiliary resistances after the extinction of the arc in the principal cutoff chambers and when there is a carry-over of voltage in one or more of the cutoff spaces,

in case of arcback, in a circuit breaker involving several cutoffs in series, then a high voltage will-appear in the control coil; the latter must therefore be very carefully insulated, which requires insulating pieces with large dimensions.

SUMMARY on THE INVENTION To avoid this inconvenience, this invention proposed a device for controllingthe opening of an auxiliary circuit breaker switch which. involves a means for detecting an appreciable current in the circuit of this auxiliary switch and a means which, due to the action of the current thus detected, will create electromagnetic forces. which will bring about the opening of the contacts of the auxiliary switch, characterized by the fact that said detection means is such fthat it presents a weak selfparticularly characteristic of the implementation of this invention, will be described below.

Another detection means consists in arranging, in series, with the auxiliary switch, a coil which itself will exert the electrodynamic forces necessary to open the auxiliary switch, but to constitute-this coil in the form of a low self-inductance coil.

This low self-inductance coil is advantageously made up of at least two windings, each of which is carried by a support and which are arranged so that the passage of an appreciable current in the coil will bring about forces between the winding supports, one of these supports being fixed and the other one of these supports being connected to a device for opening the auxiliary switch. I

Said supports can in particular be made up of plates arranged face to face and each coil winding can be made up of a conductor arranged in zig-zag fashion on one of said plates.

To increase the electrodynamic efforts, the coil may involve, between a fixed plate and a plate connected to a device for opening'the auxiliary switch, at least one intermediate plate which carries a winding on each one of its two faces.

The device for opening the auxiliary switch can simultaneously bring about the separation of the contacts of this switch and the opening of a valve which will speed up the separation of the contacts through the action of a pressurized fluid.

Referring now to the attached diagrams, we will describe examples for implementing the invention, given here without any limitations.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a device for the control of the opening of an auxiliary switch, comprising a coil wound up on a magnetic circuit around a conductor of the auxiliary switch and an indirect-action electric valve.

FIG. 2 shows an auxiliary switch opening control device of the same type, using however a direct-action electric valve.

FIGS. 3 and 4 represent two other control devices, comprising a coil positioned within a magnetic circuit around a conductor of the auxiliary switch. In the example in FIG. 3, the action triggered by the detector coil brings about the release of a lock for keeping an auxiliary switch in the closed state and, in the example in FIG. 4, an electrodynamic action, triggered by the detector coil, directly brings about the opening of the auxiliary switch. 7

FIG. 5 is a partial front view of a low-self-inductance coil element.

FIG. 6 is a partial cross-section view of an auxiliary switch control, using a coil such as the one in FIG. 5, arranged in series with the auxiliary switch.

FIG. 7 is a view of a variation of the coil in the control according to FIG. 6.

FIG. 8 is a partial cross-section view of a variation of the version according to FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS In the examples in FIGS. 1-4, an auxiliary resistance 1 is enclosed in an insulating tube 2 which also contains the auxiliary switch illustrated schematically by itsv The passage of an appreciable current in resistance 1 is detected by a coil 5, within a magnetic field surrounding a conductor of the auxiliary circuit which here is the mobile contact 4 of the switch. So long as the arc exists in the principal cutoff chamber of the circuit breaker, the voltage at the terminals of the chamber is low and the current, circulating in resistance 1, is practically negligible. When the arc extends into the principal cutoff chamber, the voltage is applied to the terminals of resistance 1 and a large current circulates in the auxiliary circuit. This current is detected by coil 5. In the case of FIG. 1, the current induced in this coil 5 supplies'the coil 6 of an electric valve 7 with pneumatic emission or with pneumatic evacuation as in the case shown, connected to a cylinder 8 in which moves a piston 9 which opens a valve 10, said opening bringing about a movement of the piston 11, which is in one piece with the mobile contact 4 which is thus separated from the fixed contact 3 and cuts the current in resistance 1, thus determining the time of insertion of the resistance.

According to the example in FIG. 2, the current induced in coil 5 by the current traversing the resistance 1 supplies a coil 12 involving a mobile core which is in one piece with a pneumatic control member 13, bringing about the movement of piston 1 1 and consequently the insertion time of resistance 1.

According to the example in FIG. 3, the current induced in coil 5 by the current traversing resistance 1 supplies a coil 14 which releases a lock 15 that'keeps the piston 11 in place, which in turn permits the movement of this piston and the opening of the circuit of resistance 1.

According to the example in FIG. 4, the current induced in the coil 5 directly, due to the action of the electrodynamic forces, pushes back the piston 1, which is in one piece with the mobile contact 4 of the switch, and permits the opening of the circuit of resistance 1.

FIG. 5 shows a coil element 16 constituted by a plate 17 in the shape of a wheel and made of insulating material, carrying a winding 18 made up of a zig-zag conductor, glued on or printed on plate 17.

As one can see in FIG. 6, two wheels 19 and 20, similar to element 16, are arranged face to face and their windings are arranged in series between them through a flexible conductor 21 and connected by connections 22 and 23 in series with an auxiliary switch for which we have shown the fixed contact 24, the mobile contact 25, the control piston 26 of this mobile contact and cylinder 27 in which the control piston moves.

Wheel 19 is fixed and wheel is mobile and is connected by a rod 28 to a valve 29 whose opening exposes to the atmosphere the volume 30 situated inside the cylinder 27 to the right of piston 26. Wheel 20 moves toward the left due to the action of the repulsion effort brought about by the passage of the current in the windings of wheels 19 and 20; this movement brings about the opening of valve 29 and, by means of a device not shown, the supply of compressed air through a duct 31 of volume 32 situated inside cylinder 27 to the left of piston 26. Piston 26 moves toward the right and separates the mobile contact from the fixed contact 24.

According to the variation FIG. 7, intermediate wheels 33, 34 (the wheels 34 are indicated only by their position) are inserted between wheels 19 and 20 and their windings are connected in series. These wheels 4 33, 34 can be equipped with a winding on each of their two faces, as illustrated for wheel 33.

In the variation in FIG. 8, a fixed wheel 35 was placed by the side of the auxiliary switch and a mobile wheel 36 was placed on the other side of the fixed wheel. Mobile wheel 36 is moved to the right when a repulsion action takes place between wheels 35 and 36. This movement brings about, at the same time, the movement of piston 26 by means of a rod 37 and the movement, by means of a rod 38, of a valve 39 which is similar to valve 29, as well as the supply of compressed air through duct 31. This arrangement permits the rapid opening of the auxiliary switch because the movement of the mobile contact is controlled directly by the coil and, as of the opening of the valve 39, this movement is accelerated pneumatically.

The arrangements according to FIGS. 5-8 facilitate great speed of operation and limitation of overvoltages. Moreover, the electrodynamic force can be adapted to the desired value, either by varying the length of the conductor constituting the winding of the wheels or by varying the number of wheels arranged in series.

The invention is used for the control of several auxiliary switches, regardless of whether a single coil, pertaining to a conductor of the circuit of only one of the auxiliary switches, simultaneously controls the opening of several auxiliary switches, each mounted parallel with one of the principal cutoff chambers, arranged in series with respect to each other, or whether each auxiliary switch has its own individual device for the detection of the instant at which the opening control must be performed.

What is claimed is:

1. In a control device for opening an auxiliary switch of a circuit breaker having a stationary contact and a mobile contact, the improvement comprising: a detection coil within a magnetic circuit around one of said contacts with said detection coil presenting a low inductance in the circuit of the auxiliary switch, and means responsive to induced current within said detection coil for causing the opening of said contacts.

2. The device according to claim 1, wherein: said coil supplies an electric valve which acts indirectly on a piston which is unitary with the mobile contact of the auxiliary switch.

3. The device according to claim 1, wherein: said coil supplies an electric valve which acts directly upon a piston which is unitary with the mobile contact of the auxiliary switch.

4. The device according to claim 1 above, wherein: said detection coil supplies a second coil which releases a locking device that is used to keep the auxiliary switch in the closed position.

5. The device according to claim 1, wherein: said detection coil directly causes the opening of an auxiliary switch through electrodynamic action, on said mobile contact.

6. In a control device for opening an auxiliary switch of a circuit breaker having a stationary contact and mobile contact, the improvement comprising: a detection coil of low self-inductance arranged in series, for exerting the electrodynamic force necessary for the opening of the auxiliary switch, said detection coil consisting of at least'two windings, each carried by a support and arranged so that the passage of an appreciable current in the coil will cause forces between the winding supports, one of said supports being fixed and another of said includes at least one intermediate plate which carries a winding on each one of its two faces.

8. The device according to claim 6, further comprising compressed fluid means for opening the auxiliary switch simultaneously to cause the separation of the contacts of this switch and the opening of a valve that speeds up the separation of the contacts. 

1. In a control device for opening an auxiliary switch of a circuit breaker having a stationary contact and a mobile contact, the improvement comprising: a detection coil within a magnetic circuit around one of said contacts with said detection coil presenting a low inductance in the circuit of the auxiliary switch, and means responsive to induced current within said detection coil for causing the opening of said contacts.
 2. The device according to claim 1, wherein: said coil supplies an electric valve which acts indirectly on a piston which is unitary with the mobile contact of the auxiliary switch.
 3. The device according to claim 1, wherein: said coil supplies an electric valve which acts directly upon a piston which is unitary with the mobile contact of the auxiliary switch.
 4. The device according to claim 1 above, wherein: said detection coil supplies a second coil which releases a locking device that is used to keep the auxiliary switch in the closed position.
 5. The device according to claim 1, wherein: said detection coil directly causes the opening of an auxiliary switch through electrodynamic action, on said mobile contact.
 6. In a control device for opening an auxiliary switch of a circuit breaker having a stationary contact and mobile contact, the improvement comprising: a detection coil of low self-inductance arranged in series, for exerting the electrodynamic force necessary for the opening of the auxiliary switch, said detection coil consisting of at least two windings, each carried by a support and arranged so that the passage of an appreciable current in the coil will cause forces between the winding supports, one of said supports being fixed and another of said supports being connected to a device for opening the auxiliary switch, said supports being made up of plates arranged face to face, with each coil winding constituting a conductor arranged in zig zag fashion on one of said plates.
 7. The device according to claim 6, wherein: said coil lies between a fixed plate and a plate connected to a device for the opening of the auxiliary switch and further includes at least one intermediate plate which carries a winding on each one of its two faces.
 8. The device according to claim 6, further comprising compressed fluid means for opening the auxiliary switch simultaneously to cause the separation of the contacts of this switch and the opening of a valve that speeds up the separation of the contacts. 